The Cryptosporidium parvum is a protozoan responsible for an oro-fecal transmitted zoonosis which until about 20 years ago was of sole veterinary interest.
Following the recent coming of the immune deficiency syndromes, mainly from HIV infections, and the increase of the treatments which cause immnunodepression in patients suffering from malignant neoplasias or submitted to organs' transplantation, an increasing diffusion of diarrhoeal events with long duration, sometimes many weeks, and of severe seriousness has occurred as reported by Meisel J. L. et al., Gastroenterology, 70, 1156-1160, (1976) and by Current W. L. and Garcia L. S., Clin. Microbiol. Rev., 4, 325-358, (1991).
Epidemiological studies carried out by Laughon B. E. et al., Gastroenterology, 94, 984-993, (1988) and by Colbunders R. et al., Am. J. Gastroenterol., 82, 859-864, (1987) on patients suffering from acquired immune deficiency syndrome (AIDS) showed that the frequency of the diarrhoea from cryptosporidiosis reaches the 10-15% of the patients suffering from AIDS in the United States to raise until 30-50% of the same persons in the developing countries.
The mechanism that causes the diarrhoeal infection is not well known; Bonnin A. and Camerlynck P., Encycl. Med. Chir. (Paris-France), Maladies Infectieuses, 8, 501-10, (1992) think toxins cholera-like that directly act on the adenylate-cyclase system of the intestinal epithelium or a secondary alteration of the villi, responsible of the passing of undigested disaccharides through the large intestine with subsequent osmotic diarrhoea, are responsible for the unleashing of the severe diarrhoeal symptomatology in patients suffering from AIDS.
The infection from Cryptosporidium parvum, after a period of incubation of about a week, in the patients suffering from AIDS appears in the shape of an aqueous profuse diarrhoea joined to strong abdominal pains, vomit, fever, cephalea and asthenia. This severe diarrhoeal form lasts for several weeks and causes severe hydroelectrolitic unbalances, dehydratation, malnutrition, renal insufficiency and, sometimes, bronchopulmonary complications in the organism already strongly weakened.
Petersen C., Clin. Infect. Dis., 15, 903-909, (1992) and Goodgame R. W. et al., J. Infect. Dis, 167, 704-709, (1993) showed a close relationship between the degree of seriousness and duration of this kind of diarrhoeal form and the degree of immunodepression: the spontaneous remission of the diarrhoeal events is observed within a month from the beginning in the patients suffering from AIDS in whom the CD4 values are yet more than 200 mm.sup.3, while the diarrhoeal pathology becomes chronic together with frequent appearance of complications in the more severe cases of immunodepression, with CD4 values lower than 100 mm.sup.3.
At present a well-established therapy of the diarrhoea from cryptosporidiosis linked to the acquired immune deficiency syndrome (AIDS) does not exist yet even if some authors reported partial results with some types of drugs. Portnoy D. et al., Ann. Intern. Med., 101, 202-204, (1984) and Connolly G. M. et al., Gut, 29, 593-597, (1988) reported initial positive results with the spiramycin, results that have not been subsequently confirmed by Wittenberg D. F. et al., J. Infect. Dis., 159, 131-132, (1989).
White A. C. Jr. et al., J. Infect. Dis., 170, 419-424, (1994) and Walmsley S. et al., Program and abstracts: IX Intemational Conference on AIDS/IV STD World Congress (Berlin). London: Wellcome Foundation, (1993) reported significant clinical and parasitologic improvements with a treatment based on an administration of 2 g a day of paramomicin for two or more weeks, but any parasitologic eradication has not been obtained as showed in the 58% of recidivations.
Finally Vargas S. L. et al., J. Pediatr., 123, 154-156, (1993) and Dunne M. W., Program and abstracts: IX International Conference on AIDS/IV STD World Congress (Berlin). London: Wellcome Foundation, (1993) showed initial effectiveness proofs by using high doses of azitromycin.